[Antz]

My fathers T5 has this exact same problem and we are stumped too. Every now and again itll start and run fine but 19 out of 20 attempts itll just crank over. Every time we think we have solved it, itll drive fine and then do it again later on.

Symptoms:
# Intermittent non-starting
# When it starts it runs and drives perfectly fine with no codes
# When it doesn’t start the automatic UP arrow on the dashboard flashes with ignition turned on
# When it doesn’t start the Economy/Sport switch flashes with ignition turned on
# When it doesn’t start there is No spark (we have fuel)
# When it doesn’t start a cheapy code reader keeps flashing up Throttle position sensor

What we have done:
# Replaced crank sensor
# Replaced cam sensor
# Replaced throttle positon sensor
# Replaced throttle body
# Replaced spark plugs
# Replaced coil pack
# Replaced ignition leads
# Replaced turbo vac lines
# Tried a different MAF and tried it with the MAF disconnected
# Tried the original engine ECU (currently running a T5R ECU which has been fine for the past 5 years)
# checked and changed the relay behind front panel

We are lost for ideas now.